bleaching wood

Ed Blakeslee

Curious about Wooden Canoes
I have just about finished stripping my Old Town. Things look pretty good but there are a few stains. Should I try to bleach them and if so with what product or just say you are 80 years old so a few spots are ok?
You've got lots of choices. Depending on the source of the stain you may have luck with a solution of oxalic acid. This is especially useful for the black stains from iron fasteners. You can get powdered oxalic acid and mix your own or get premixed in formulations for bleaching wood decks and fences. Another choice is the single or two-part teak cleaners available from marine supply stores. If you're not careful, these can be pretty harsh on soft cedar, though. Finally, you could try chlorine bleach, but I've not had much luck with it.

Whatever you go with, you'll want to treat the whole canoe rather than spot treat. This will assure a more uniform look when you're done. Of course, you could opt not to treat and accept, as you say, that a few age spots simply reflect on the age of the canoe. Good luck.
This is one of my favorite parts of the process. Use a quality 2-part cleaner/bleach such as Te-Ka or Snappy Teak-Nu. I've tried many and these are the only ones I've found that do a reasonable job. Store brands do little or nothing, and all of these treatments are not of the same chemical formula. Instructions say not to use on mahogany, but in my experience on many boats, they pose no problems for mahogany, and in fact clean it beautifully while leaving it and all other wood with an even beautiful patina. The instructions on many also say "scrub-less" or "no need to scrub". Not true- use a soft nylon brush to scrub the treated surface if you really want to clean it.

Are these things too harsh? One British book says never use them, but in fact, they pose no real harm (again, in my experience) to even soft woods like cedar. Yes, the surface becomes fuzzed a but, but sanding with 120 followed by 220 makes a beautiful surface for varnish.

Finally, oxalic acid- wonderful for iron stains. If you had any iron fasteners, use it to remove black iron stains. It also works on black stains in tannin-laden woods like white oak. Make a concentrated (saturated) solution, and paint it on. You'll see iron stains disappear before your eyes. I've heard all sorts of ideas on neutralization of the acid, but use only water- the oxalic acid is readily soluble in water, so it will wash away. I've even read that you should neutralize with vinegar (acetic acid will not neutralize oxalic acid!), or that you should use a base like sodium hydroxide. A base like NaOH will neutralize an acid, but it can also turn wood black!

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To add to Mikes comments,

I've also mainly used the 2 brands he quoted but, on the last project, due to running out I picked up a small amount of another brand from Menards, I "think" it was Parks or Dr Somebody's, anyway, even though the 1 of the chemicals was the same, the other was different, and this brand really left the wood looking like new, much better then the other 2 brands.

I'm going to try to get a larger amount for the next project and try to confirm/disprove whether it indeed was better.


I just finished bleaching my '52 OTCA with surprising results. This canoe has been in use every summer since '52 and not a drop of varnish has ever been put on it. It was obviously very easy to strip what was left of the varnish but most of the canoe was badly weathered. The first application of Te-Ka two part brightner helped. I bleached it a second time thanks to Michael Grace's tip that, contray to the directions, you must leave part A on for at least 10 minutes and scurb and scurb with a not too hard and not too soft brush and flush very well with the part B. Let the canoe dry out, knock off the resulting 'wood fuzz' with sandpaper and it is ready to varnish. It looks great.

Thanks for the information. This is a family project so I'll let my friends decide to the next step. I have two questions though. The oxalic acid box instructions say one pound per gallon of water. I think I probally need two gallons of mix for an 18 foot canoe. And how much Te-Ka do you think I would need? I have only seen it in pint containers. Thanks for your help. Ed
For oxalic acid, I don't measure, but make a saturated solution- that is, a solution that is holding all the oxalic acid it can, with the rest as crystals on the bottom. Not a big deal, though. It doesn't take much oxalic acid to clear those stains. If the surface dries quickly after applying, add more to make sure you're getting good penetration.

A quart of each part of the 2-part system should be plenty. I've never seen Te-Ka or Snally Teak-Nu for sale in anything but a 2-quart kit. I started buying in gallon jugs from the manufacturer, though, some time ago. MUCH cheaper if you go through a lot of it. Oh- Chuck Hoffhine reminded me by email to mention that some woods tend to fuzz up more than others. Birch does, and it takes good diligent sanding to get it smooth. Old spruce is even worse, but sand good, apply sealer coat of thinned varnish, let dry completely, and sand good again. Should be smooth and without any significant surface loss.

I haven't seen any mention of just using boiled linseed oil in lieu of bleaching. I'm approaching the same point with a restoration project. I realize the oil will give the wood a dark color but are there some of you out there who have gone this way? Suggestions?
John Greer said:
I haven't seen any mention of just using boiled linseed oil in lieu of bleaching. I'm approaching the same point with a restoration project. I realize the oil will give the wood a dark color but are there some of you out there who have gone this way? Suggestions?
I used linseed on the interior of my canoe at the end of a summer of weekends stripping the whole canoe. Then I put it away for the winter. In the spring the 'Art museum' smell was gone & the interior surface was dull & a litle darker. I sanded & varnished two coats before turning to finishing the exterior. The amount of moisture this adds to the canoe is questionable. It was a good visual to see how the stripped interior would look when varnished, like using a tac cloth, but the effect stays. After replacing the cane inserts the whole interior received another coar with the thwarts, decks, rails & seats repeated for extra protection to abrasion from use.
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Thanks Mark. How did you like the finished project? Would you do it again? I've not yet decided which way I'll go. At this point it's all stripped, new inside rails, replaced stem tips, deck. Have just a few ribs to replace then it's ready for finish work.
The Avitar picture is the rear deck of my canoe & my profile picture is a close up of the serial number. Both give a good example of the results. I think the absorbtion of the linseed gave the stripped interior a nice patina.

The interior has been covered with a dark stain varnish & when I was stripping, I'd stop and examine my progress, viewing from the stern seat. I find I left quite a few little dark bits here & there; mostly in the stern where I don't see most of them.

If I had replaced a ton of ribs I might have bleached the old stuff to even out the wood tones...overall I'm happy that I used the oil and I don't feel it darkend things that much; my 'sistered' ribs are lighter but not so much that it screams out...
Thanks Mark. I'll probably go with the oil like I had planned. Have about 8 ribs total to replace and if I want I can always give them a light stain.

Great weather out here in Montana today. Think I"m going to put my boat (jet) in the river and give my dog a ride this afternoon. Canoe tomorrow.